In recent years, there has been an increasing expectation on large-shield wall-hung televisions for use as bidirectional information terminals. As display devices for this purpose, many types of displays are available such as a liquid crystal display panel, a field emission display and an electroluminescent display. Among them, a plasma display panel (hereinafter referred to as PDP) is drawing attention as a flat display device with good visibility because of self-luminescence, ability to display beautiful pictures, and ease of realizing larger shield sizes, and efforts are being made to achieve higher definition and larger shield sizes.
Driving schemes of PDP can be broadly divided into an AC type and a DC type. Thebacke two types of discharge schemes, namely, surface discharge type and opposing discharge type. Currently, AC type and surface discharge type PDP's are dominant from standpoints of achieving higher definition and larger shield, and simplicity of manufacturing.
FIG. 20 shows an example of a conventional PDP panel structure. As illustrated in FIG. 20, this PDP is comprised of front panel 1 and back panel 2.
Front panel 1 is comprised of transparent front substrate 3, a plurality of display electrodes 6, dielectric layer 7, and protective film 8. Front substrate 3 is a glass substrate such as made from boron silicide sodium glass fabricated by a floating method. Each display electrode 6 consists of a scan electrode 4 and sustain electrode 5, and a plurality of these pairs are laid out on front substrate 3 in a striped manner. Dielectric layer 7 is formed in a manner covering a group of display electrodes 6, and protective film 8 made from MgO is formed on dielectric layer 7.
Here, scan electrode 4 and sustain electrode 5 consist of transparent electrodes 4a, 5a that serve as discharge electrodes and bus electrodes 4b, 5b that are electrically connected with transparent electrodes 4a, 5a, respectively. Bus electrodes 4b, 5b are formed from such material as Cr/Cu/Cr, Ag or the like.
Back panel 2 consists of back substrate 9, address electrodes 10, dielectric layer 11, a plurality of stripe-shaped barrier ribs 12, and phosphor layers 13. Address electrodes 10 are formed on back substrate 9 that is disposed opposite front substrate 3 in a direction orthogonal to display electrodes 6. Dielectric layer 11 is formed in a manner covering address electrodes 10. Ribs 12 are formed on dielectric layer 11 between address electrodes 10 and in parallel to address electrodes 10. Phosphor layer 13 is formed on sides between ribs 12 and on a surface of dielectric layer 11. Here, for a purpose of displaying colors, phosphor layer 13 normally consists of three sequentially disposed colors of red, green, and blue. Front and back panels 1, 2 are opposed to each other across a minute discharge space with display electrodes 6 orthogonal to address electrodes 10, and their periphery is sealed with a sealing member. A discharge space is filled with discharge gas, which is made by mixing for example, neon (Ne) and xenon (Xe), at a pressure of about 66,500 Pa (500 Torr). In this way, the PDP is formed.
The discharge space of this PDP is partitioned into a plurality of sections by barrier ribs 12, and a plurality of discharge cells or light-emitting pixel regions is each defined by barrier ribs 12 and display and address electrodes 6, 10 that are orthogonal to each other.
With this PDP, discharge is caused by periodic application of voltage to address electrode 10 and display electrode 6, and ultraviolet rays generated by this discharge are applied to phosphor layer 13, thereby being converted into visible light. In this way, an image is displayed.
As shown in FIG. 14, scan and sustain electrodes 4, 5 of display electrode 6 are disposed with discharging gap 14 between these electrodes 4, 5. Light-emitting pixel region 15 is a region surrounded by this display electrode 6 and barrier ribs 12, and non-light-emitting pixel region 16 is an adjoining gap or region between adjacent display electrodes 6. Also, a black stripe is sometimes formed in non-light-emitting pixel region 16 for a purpose of improving contrast.
For development of a PDP, further effort toward higher luminance, higher efficiency, lower power consumption, and lower cost are essential. In order to achieve a higher efficiency, it is essential to control discharge in each region of each light-emitting pixel. Especially in an area of spread of discharge perpendicular to display electrodes 6, as bus electrodes 4b, 5b shield light emitted by the phosphor, it is effective to control discharge from spreading to a shielded area.
As an approach to efficiency improvement, a method is known, as disclosed in Japanese Patent Laid-Open Application No. H8-250029, for example, in which discharge in an area shielded by bus electrodes 4b, 5b is suppressed by increasing a thickness of dielectric layer 7 on bus electrodes 4b, 5b. 
However, in the conventional structure as described above, although discharge in a direction perpendicular to the display electrodes is suppressed, discharge in a direction parallel to the display electrodes is not suppressed and spreads to a neighborhood of barrier ribs. In this case, there is a possibility of lowering of an electron temperature due to ribs and reduction in efficiency due to occurrence of recombination of electrons and ions.